Warden Myfyr Tomos added: “On the Tŷ Nant footpath, within less than a mile between Rhiw Gwredydd and Bwlch y Cyfrwy, there are 102 cairns, and at the base of each cairn a very large hole where stones have been lifted from the path and adjacent land.

“Some of the stones are huge and the cairns are increasing every week.

“We need to ensure that future generations can enjoy walking the paths and mountains of Snowdonia. Reducing erosion by encouraging people not to move the stones is a way of contributing to this.”

Paul Williams, manager of the Cadair Idris Nature Reserve on behalf of Natural Resources Wales said: “Building’ cairns has been of great concern over a number of years – the practice, by now, is totally unreasonable, creating scars on some of our most significant landscapes.

“The practice damages fragile habitats such as the moorland in the uplands and the scree, together with the animals and the plants associated with them.

“A cairn should only show the summit of a mountain where historical cairns are already there.”